Under Latin Rite theology, the consecration is not complete (and thus not effective) unless both elements are consecrated. Thus, the bread would have remained bread, and the wine would have obviously remained wine.
This is not at all true. In fact, the very fact that it
can be done is why we have Canon 927 of the CIC:
Can. 927 It is absolutely forbidden, even in extreme urgent necessity, to consecrate one matter without the other or even both outside the eucharistic celebration.
As to the OP’s questions, yes, the Consecration was completely valid in this case, and the priest did exactly the right thing once he realized his omission. This is hardly the first time in history that such a thing has happened. But no,
I have never seen it happen!
I should point out that if the priest had
not corrected his mistake, then (1) the bread would have been consecrated (it already was by the time he elevated it after saying “This is my Body”), (2) the wine would have remained ordinary unconsecrated wine, (3) people who received Communion under the species of bread would have received the entire Body, Blood, Soul, and Divinity of Christ, just like always, and (4) although the Eucharist was valid as regards the bread, the ceremony
in toto would not have been a Mass, since Mass requires both elements of the sacrifice. It just would have been a big blunder.